McGuard prop locks with XR shaft
 

I am curious about the mounting of the prop on an XR large shaft, I replaced the prop hub and the standard installation requires 3 washers, one large flat, one medium "spring" washer and one more flat washer, then the prop nut. I replaced the prop nut with the McGuard nut and "spring washer" that comes with the lock kit. Now on the shaft I have two "Spring washers" and am concerned that maybe I should only use one. Could or will two of them cause the prop to be too loose? Suggestions?

No problem
 

The two spring washers can't hurt you- unless you are concerned about a few grams extra flywheel weight;)

When you torque the nut the spring washers flatten out to give full metal to metal contact on each side. The spring washers give an extra measure of protection if the nut were to back off slightly or in an environment with different thermal expansion rates which could cause play in the stack. In this reqard two spring washers give twice the protection.

Just make sure you still have about 1.5 thread sticking out past the nylon locking feature of the nut and it would not hurt to retorque the nut every 10-20 hrs for piece of mind.

Good luck:D